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Tue, 07 Jul 2026 05:00:01 -0700 (PDT) Received: from localhost.localdomain ([192.197.201.174]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-311747f596asm7785716eec.2.2026.07.07.04.59.59 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Tue, 07 Jul 2026 05:00:00 -0700 (PDT) From: =?UTF-8?q?HE=20WEI=20=28=E3=82=AE=E3=82=AB=E3=82=AF=29?= To: Johannes Berg Cc: linux-wireless@vger.kernel.org, linux-kernel@vger.kernel.org, Sara Sharon , Luca Coelho , =?UTF-8?q?HE=20WEI=20=28=E3=82=AE=E3=82=AB=E3=82=AF=29?= Subject: [PATCH v3] wifi: cfg80211: bound element ID read when checking non-inheritance Date: Tue, 7 Jul 2026 20:59:54 +0900 Message-ID: <20260707115954.21721-1-skyexpoc@gmail.com> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260626144543.5034-1-skyexpoc@gmail.com> References: <20260626144543.5034-1-skyexpoc@gmail.com> Precedence: bulk X-Mailing-List: linux-wireless@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit cfg80211_is_element_inherited() reads the first data octet of the candidate element (id = elem->data[0]) to look it up in an extension non-inheritance list. It does so after testing elem->id, but without verifying that the element actually has a data octet. A zero-length extension element (WLAN_EID_EXTENSION with length 0) therefore makes it read one octet past the end of the element. _ieee802_11_parse_elems_full() runs this check for every element of a frame once a non-inheritance context exists -- e.g. while parsing a per-STA profile of a Multi-Link element in a (re)association response, or a non-transmitted BSS profile -- so a crafted frame from an AP can trigger a one-octet slab-out-of-bounds read during element parsing: BUG: KASAN: slab-out-of-bounds in cfg80211_is_element_inherited Read of size 1 ... in net/wireless/scan.c Return early (treat the element as inherited) when an extension element carries no data, mirroring the existing handling of empty ID lists. The bug was found by fuzzing ieee802_11_parse_elems_full() under KASAN. Fixes: f7dacfb11475 ("cfg80211: support non-inheritance element") Signed-off-by: HE WEI (ギカク) --- Changes in v3: - Move the version changelog below the --- line and trim the Fixes commit id to 12 characters (checkpatch). Changes in v2: - Correct the Fixes tag. The unchecked elem->data[0] read was introduced in 2019 by f7dacfb11475 ("cfg80211: support non-inheritance element") -- the commit that added cfg80211_is_element_inherited() -- not by dfd9aa3e7a45, which only rewrote the sibling cfg80211_gen_new_ie() and never touched this function. net/wireless/scan.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/wireless/scan.c b/net/wireless/scan.c index 05b7dc6b7..0a44856b1 100644 --- a/net/wireless/scan.c +++ b/net/wireless/scan.c @@ -205,7 +205,7 @@ bool cfg80211_is_element_inherited(const struct element *elem, return true; if (elem->id == WLAN_EID_EXTENSION) { - if (!ext_id_len) + if (!ext_id_len || !elem->datalen) return true; loop_len = ext_id_len; list = &non_inherit_elem->data[3 + id_len]; -- 2.43.0